Reconfigurable Orthogonal Frequency Division Multiplexing (OFDM) Chip Supporting Single Weight Diversity

ABSTRACT

A method and system for a reconfigurable orthogonal frequency division multiplexing (OFDM) chip supporting single weight diversity are provided. The reconfigurable OFDM chip may be configured to process signals such as IEEE 802.11, 802.16, and digital video broadcasting (DVB). The OFDM chip may generate channel weights to be applied to signals received in receive antennas. The weighted signals may be combined into a single received signal and channel estimates may be generated from the single received signal. Updated channel weights may be generated from the generated channel estimates. Updates to the channel weights may be performed dynamically. The configurable OFDM chip may be utilized to provide collaborative cellular and OFDM-based communication. The reconfigurable OFDM chip and the cellular chip may communicate data and/or control information via a memory coupled to a common bus.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

The present application is a continuation of U.S. Non-Provisionalapplication Ser. No. 11/237,328, filed Sep. 28, 2005, which is acontinuation-in-part of U.S. application Ser. No. 10/645,349, filed onAug. 21, 2003, which makes reference to, claims priority to and claimsbenefit from U.S. Provisional Patent Application Ser. No. 60/405,285filed on Aug. 21, 2002.

This application makes reference to:

U.S. application Ser. No. 11/237,002 filed Sep. 28, 2005; and

U.S. application Ser. No. 11/237,045 filed Sep. 28, 2005.

Each of the above stated applications is hereby incorporated byreference in its

entirety.

FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT

[Not Applicable]

MICROFICHE/COPYRIGHT REFERENCE

[Not Applicable]

FIELD OF THE INVENTION

Certain embodiments of the invention relate to processing of signals incommunication systems. More specifically, certain embodiments of theinvention relate to a reconfigurable orthogonal frequency divisionmultiplexing (OFDM) chip supporting single weight diversity.

BACKGROUND OF THE INVENTION

Mobile communications has changed the way people communicate and mobilephones have been transformed from a luxury item to an essential part ofevery day life. The use of mobile devices is today dictated by socialsituations, rather than hampered by location or technology. While voiceconnections fulfill the basic need to communicate, and mobile voiceconnections continue to filter even further into the fabric of every daylife, the mobile Internet is the next step in the mobile communicationrevolution. The mobile Internet and/or mobile video are poised to becomea common source of everyday information, and easy, versatile mobileaccess to this data will be taken for granted.

Third generation (3G) cellular networks, for example, have beenspecifically designed to fulfill these future demands of the mobiledevices. As these services grow in popularity and usage, factors such ascost efficient optimization of network capacity and quality of service(QoS) will become even more essential to cellular operators than it istoday. These factors may be achieved with careful network planning andoperation, improvements in transmission methods, and advances inreceiver techniques. To this end, carriers need technologies that willallow them to increase downlink throughput and, in turn, offer advancedQoS capabilities and speeds that rival those delivered by cable modemand/or DSL service providers. In this regard, networks based on widebandCDMA (WCDMA) technology may make the delivery of data to end users amore feasible option for today's wireless carriers. The GPRS and EDGEtechnologies may be utilized for enhancing the data throughput ofpresent second generation (2G) systems such as GSM. Moreover, HSDPAtechnology is an Internet protocol (IP) based service, oriented for datacommunications, which adapts WCDMA to support data transfer rates on theorder of 10 megabits per second (Mbits/s).

In addition to cellular technologies, technologies such as thosedeveloped under the IEEE 802.11 and 802.16 standards, and/or the digitalvideo broadcasting (DVB) standard, may also be utilized to fulfill thesefuture demands of the mobile devices. For example, wireless local areanetworks (WLAN), wireless metropolitan area networks (WMAN), and DVBnetworks may be adapted to support mobile Internet an/or mobile videoapplications, for example. The digital video broadcasting (DVB)standard, for example, is a set of international open standards fordigital television maintained by the DVB Project, an industryconsortium, and published by a Joint Technical Committee (JTC) ofEuropean Telecommunications Standards Institute (ETSI), EuropeanCommittee for Electrotechnical Standardization (CENELEC) and EuropeanBroadcasting Union (EBU). The DVB systems may distribute data bysatellite (DVB-S), by cable (DVB-C), by terrestrial television (DVB-T),and by terrestrial television for handhelds (DVB-H). The standards maydefine the physical layer and data link layer of the communicationsystem. In this regard, the modulation schemes used may differ inaccordance to technical and/or physical constraints. For example, DVB-Smay utilize QPSK, DVB-C may utilize QAM, and DVB-T and DVB-H may utilizeOFDM in the very high frequency (VHF)/ultra high frequency (UHF)spectrum.

These networks may be based on frequency division multiplexing (FDM).The use of FDM systems may result in higher transmission rates byenabling the simultaneous transmission of multiple signals over a singlewireline or wireless transmission path. Each of these signals maycomprise a carrier frequency modulated by the information to betransmitted. In this regard, the information transmitted in each signalmay comprise video, audio, and/or data, for example. The orthogonal FDM(OFDM) spread spectrum technique may be utilized to distributeinformation over many carriers that are spaced apart at specifiedfrequencies. The OFDM technique may also be referred to as multi-carrieror discrete multi-tone modulation. The spacing between carriers preventsthe demodulators in a radio receiver from seeing frequencies other thantheir own. This technique may result in spectral efficiency and lowermulti-path distortion, for example.

In both cellular and OFDM-based networks, the effects of multipath andsignal interference may degrade the transmission rate and/or quality ofthe communication link. In this regard, multiple transmit and/or receiveantennas may be utilized to mitigate the effects of multipath and/orsignal interference on signal reception and may result in an improvedoverall system performance. These multi-antenna configurations may alsobe referred to as smart antenna techniques. It is anticipated that smartantenna techniques may be increasingly utilized both in connection withthe deployment of base station infrastructure and mobile subscriberunits in cellular systems to address the increasing capacity demandsbeing placed on those systems. These demands arise, in part, from ashift underway from current voice-based services to next-generationwireless multimedia services that provide voice, video, and datacommunication.

The utilization of multiple transmit and/or receive antennas is designedto introduce a diversity gain and to suppress interference generatedwithin the signal reception process. Such diversity gains improve systemperformance by increasing received signal-to-noise ratio, by providingmore robustness against signal interference, and/or by permittinggreater frequency reuse for higher capacity. In communication systemsthat incorporate multi-antenna receivers, a set of M receive antennasmay be utilized to null the effect of (M−1) interferers, for example.Accordingly, N signals may be simultaneously transmitted in the samebandwidth using N transmit antennas, with the transmitted signal thenbeing separated into N respective signals by way of a set of N antennasdeployed at the receiver. Systems that utilize multiple transmit andreceive antennas may be referred to as multiple-input multiple-output(MIMO) systems. One attractive aspect of multi-antenna systems, inparticular MIMO systems, is the significant increase in system capacitythat may be achieved by utilizing these transmission configurations. Fora fixed overall transmitted power, the capacity offered by a MIMOconfiguration may scale with the increased signal-to-noise ratio (SNR).For example, in the case of fading multipath channels, a MIMOconfiguration may increase system capacity by nearly M additionalbits/cycle for each 3-dB increase in SNR.

However, the widespread deployment of multi-antenna systems in wirelesscommunications, particularly in wireless handset devices, has beenlimited by the increased cost that results from increased size,complexity, and power consumption. Providing separate RF chain for eachtransmit and receive antenna is a direct factor that increases the costof multi-antenna systems. Each RF chain generally comprises a low noiseamplifier (LNA), a filter, a downconverter, and an analog-to-digitalconverter (A/D). In certain existing single-antenna wireless receivers,the single required RF chain may account for over 30% of the receiver'stotal cost. It is therefore apparent that as the number of transmit andreceive antennas increases, the system complexity, power consumption,and overall cost may increase. This poses problems for mobile systemdesigns and applications.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the remainder of the present application with reference tothe drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method is provided for a reconfigurable orthogonalfrequency division multiplexing (OFDM) chip supporting single weightdiversity, substantially as shown in and/or described in connection withat least one of the figures, as set forth more completely in the claims.

These and other features and advantages of the present invention may beappreciated from a review of the following detailed description of thepresent invention, along with the accompanying figures in which likereference numerals refer to like parts throughout.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a block diagram illustrating an exemplary cellular and OFDMcollaboration system with single channel weight diversity, in accordancewith an embodiment of the invention.

FIG. 1B is a flow chart illustrating exemplary steps for cellular andOFDM collaboration, in accordance with an embodiment of the invention.

FIG. 1C is a block diagram illustrating an exemplary reconfigurable OFDMchip with single channel weight diversity, in accordance with anembodiment of the invention.

FIG. 2A is a block diagram of an exemplary two-transmit (2-Tx) andtwo-receive (2-Rx) antennas wireless communication system with receiverchannel estimation, in accordance with an embodiment of the invention.

FIG. 2B is a block diagram of an exemplary two-transmit (2-Tx) andmultiple-receive (M-Rx) antennas wireless communication system withreceiver channel estimation, in accordance with an embodiment of theinvention.

FIG. 3A is a flow diagram illustrating exemplary steps for channelestimation in a 2-Tx and M-Rx antennas wireless communication system, inaccordance with an embodiment of the invention.

FIG. 3B illustrates an exemplary periodic phase rotation for an in-phase(I) signal received in one of the additional receive antennas, inaccordance with an embodiment of the invention.

FIG. 4A is a block diagram of an exemplary single weight basebandgenerator (SWBBG) that may be utilized in a 2-Tx and 2-Rx antennassystem, in accordance with an embodiment of the invention.

FIG. 4B is a block diagram of an exemplary single weight basebandgenerator (SWBBG) that may be utilized in a 2-Tx and M-Rx antennassystem, in accordance with an embodiment of the invention.

FIG. 4C is a block diagram of an exemplary RF phase and amplitudecontroller, in accordance with an embodiment of the invention.

FIG. 5 is a flow diagram illustrating exemplary steps in the operationof the single weight baseband generator (SWBBG) that may be utilized forchannel estimation in a 2-Tx and M-Rx antennas system, in accordancewith an embodiment of the invention.

FIG. 6 is a block diagram of an exemplary channel estimator for a 2-Txand 2-Rx antennas system, in accordance with an embodiment of theinvention.

FIG. 7 is a flow diagram illustrating exemplary steps for channelestimation based on complex multiplication and integration of a firstand second baseband combined channel estimates, in accordance with anembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention may be found in a system and/ormethod for a reconfigurable orthogonal frequency division multiplexing(OFDM) chip supporting single weight diversity. In accordance withvarious embodiments of the invention, the reconfigurable OFDM chip maybe configured to process signals such as IEEE 802.11, 802.16, anddigital video broadcasting (DVB). The OFDM chip may generate channelweights to be applied to signals received in receive antennas. Theweighted signals may be combined into a single received signal andchannel estimates may be generated from the single received signal.Updated channel weights may be generated from the generated channelestimates. Updates to the channel weights may be performed dynamically.The configurable OFDM chip may be utilized to provide collaborativecellular and OFDM-based communication. The reconfigurable OFDM chip andthe cellular chip may communicate data and/or control information via amemory coupled to a common bus.

FIG. 1A is a block diagram illustrating an exemplary cellular and OFDMcollaboration system with single channel weight diversity, in accordancewith an embodiment of the invention. Referring to FIG. 1A, there isshown a mobile terminal 150 that may comprise a cellular block 152, anOFDM block 154, a processor 156, a memory 158, and a common bus 160. TheOFDM block 154 may comprise a plurality of registers 157. The mobileterminal 150 may be utilized for receiving and/or transmitting cellularand/or OFDM-based information, such as DVB-H information for example.The cellular block 152 may comprise suitable logic, circuitry, and/orcode that may be adapted to process cellular information. The cellularblock 152 may be adapted to transmit cellular information via at leastone transmit antenna. In this regard, there are shown K transmitantennas 153 a (Tx_(—)0), . . . , 153 b (Tx_K−1). When K>1 the cellularblock 152 may support transmit diversity techniques, for example. Thecellular block 152 may also be adapted to receive cellular informationvia at least one receive antenna. In this regard, there are shown Lreceive antennas 153 c (Rx_(—)0), . . . , 153 d (Rx_L−1). When L>1 thecellular block 152 may support receive diversity techniques, forexample. The cellular block 152 may be adapted to support at least oneof a plurality of cellular technologies such as CDMA, WCDMA, HSDPA, GSM,and/or UMTS, for example.

The cellular block 152 may be adapted to transfer data and/or controlinformation to the OFDM block 154 via the common bus 160. In someinstances, the cellular block 152 may transfer data and/or controlinformation to the OFDM block 154 via the common bus 160 directly. Inother instances, the data and/or control information may be firsttransferred from the cellular block 152 to the memory 156 via the commonbus 160 and then transferred from the memory 156 to the OFDM block 154via the common bus 160.

The OFDM block 154 may comprise suitable logic, circuitry, and/or codethat may be adapted to process information communicated by OFDMmodulation techniques. The OFDM block 154 may be adapted to transmitinformation via at least one transmit antenna. In this regard, there areshown R transmit antennas 155 a (Tx_(—)0), . . . , 155 b (Tx_R−1). WhenR>1 the OFDM block 154 may support transmit diversity techniques, forexample. An exemplary diversity technique that may be utilized by theOFDM block 154 for transmission is single weight diversity. The OFDMblock 154 may also be adapted to receive information via at least onereceive antenna. In this regard, there are shown P receive antennas 155c (Rx_(—)0), . . . , 155 d (Rx_P−1). When P>1 the OFDM block 154 maysupport receive diversity techniques, for example. An exemplarydiversity technique that may be utilized by the OFDM block 154 forreception is single weight diversity. U.S. application Ser. No.11/173,964, U.S. application Ser. No. 11/173,252, and U.S. applicationSer. No. 11/174,252 provide a detailed description of channel estimationand single weight generation and are hereby incorporated herein byreference in their entirety. The OFDM block 154 may be adapted tosupport at least one of a plurality of OFDM-based technologies such aswireless local area networks (WLANs) based on IEEE 802.11, wirelessmetropolitan area networks (WMANs) based on 802.16, and digital videobroadcasting for handhelds (DVB-H), for example.

The OFDM block 154 may be adapted to transfer data and/or controlinformation to the cellular block 152 via the common bus 160. In someinstances, the OFDM block 154 may transfer data and/or controlinformation to the cellular block 155 via the common bus 160 directly.In other instances, the data and/or control information may be firsttransferred from the OFDM block 154 to the memory 156 via the common bus160 and then transferred from the memory 156 to the OFDM block 154 viathe common bus 160.

The OFDM block 154 may be a configurable device and at least a portionof the OFDM block 154 may be configured in accordance with one of theOFDM technologies that may be supported. For example, certain aspects inthe OFDM block 154 that may be configured may comprise forward errorcorrection (FEC), parsing, interleaving, mapping, fast Fouriertransformations (FFTs), and/or guard interval insertion. Other aspectsof the OFDM block 154 that may be configured may comprise operatingbandwidth, auto detection of multiple preambles, channel estimation,and/or header cyclic redundancy check (CRC) length, for example. In thisregard, the plurality of registers 157 may comprise suitable logic,circuitry, and/or code that may be adapted to store values and/orparameters that correspond to the configurable aspects of the OFDM block154. To configure the OFDM block 154, the values and/or parameters to bestored in the plurality of registers 157 may be transferred from thememory 158 via the common bus 160 based on at least one control signalgenerated by the processor 156, for example.

The processor 156 may comprise suitable logic, circuitry, and/or codethat may be adapted to perform control and/or management operations forthe mobile terminal 150. In this regard, the processor 156 may beadapted to generate at least one signal for configuring the OFDM block154. Moreover, the processor 156 may be adapted to arbitrate and/orschedule communications between the cellular block 152 and the OFDMblock 154 when collaborative communication is to be utilized. In someinstances, the arbitration and/or scheduling operation may be performedby logic, circuitry, and/or code implemented separately from theprocessor 156. The processor 156 may also be adapted to control singleweight diversity operations in the OFDM block 154. For example, theprocessor 156 may control the integration time utilized when generatingchannel weights for receive and/or transmit antennas in the OFDM block154. The memory 158 may comprise suitable logic, circuitry, and/or codethat may be adapted to store information that may be utilized by thecellular block 152, the OFDM block 154, and/or the processor 156. Inthis regard, the memory 158 may store parameters associated with thevarious configurations supported by the OFDM block 154.

In operation, when an OFDM configuration mode has been selected, theprocessor 156 may generate at least one signal to transfer configurationinformation from the memory 156 to the plurality of registers 157 in theOFDM block 154 via the common bus 160. In this regard, exemplary OFDMconfiguration modes may comprise WLAN modes, WMAN modes, and DVB-Hmodes. The OFDM block 154 may receive and transmit information inaccordance to the OFDM configuration mode currently supported.Similarly, the cellular block 152 may receive and/or transmit cellularinformation. When single weight diversity is supported by the transmitand/or receive operations of the OFDM block 154, appropriate channelweights may be generated by the OFDM block 154 to at least one of thetransmit antennas 155 a (Tx_(—)0), . . . , 155 b (Tx_R−1) and/or at lestone of the receive antennas 155 c (Rx_(—)0), . . . , 155 d (Rx_P−1).

When cellular communication may be more efficiently performed via theOFDM block 154, the processor 156 may coordinate the transfer ofinformation from the cellular block 152 to the OFDM block 154. In thisregard, information from the cellular block 152 may be transferred tothe memory 158 and then from the memory 158 to the OFDM block 154.Similarly, when OFDM-based communication may be more efficientlyperformed via the cellular block 152, the processor 156 may coordinatethe transfer of information from the OFDM block 154 to the cellularblock 152. In this regard, information from the OFDM block 154 may betransferred to the memory 158 and then from the memory 158 to thecellular block 152.

FIG. 1B is a flow chart illustrating exemplary steps for cellular andOFDM collaboration, in accordance with an embodiment of the invention.Referring to FIG. 1B, there is shown a flow diagram 170 forcollaborative operation of cellular and OFDM communication in the mobileterminal 150 in FIG. 1A. After start step 172, in step 174, theprocessor 156 may configure the OFDM block 154 to operate in one of aplurality of OFDM configuration modes. The parameters that support eachOFDM configuration mode may be transferred to the plurality of registers157 in the OFDM block from the memory 156.

In step 176, the processor 156 may arbitrate and/or schedulecollaborative communication between the cellular block 152 and the OFDMblock 154. In this regard, the processor 156 may determine, based oninformation provided by the cellular block 152 and/or the OFDM block154, whether cellular data may be communicated by utilizing the OFDMblock 154 or whether OFDM-based information may be communicated byutilizing the cellular block 152. For example, when the quality of WCDMAcommunication link supported by the cellular block 152 becomes low andthe transmission rate via that WCDMA communication link degrades, thecellular block 152 may generate a signal to the processor 156 to provideaccess to the cellular data to its recipient via the OFDM block 154.Similarly, when the quality of WLAN communication link supported by theOFDM block 154 becomes low and the transmission rate via that WLANcommunication link degrades, the OFDM block 154 may generate a signal tothe processor 156 to provide access to the WLAN information to itsrecipient via the cellular block 152. In either case, the processor 156may request information from the other block to determine whether thenecessary resources for collaboration are available. When the resourcesare available, collaboration between the OFDM block 154 and the cellularblock 152 may be implemented.

In step 178, when the processor 156 determines that cellular data may besent via the OFDM block 154, that is, collaboration may be implemented,the process may proceed to step 180. In step 180, the cellular data maybe transferred to the OFDM block 154 from the cellular block 152 via thecommon bus 160. In this regard, the cellular data may be first stored inthe memory 158 before final transfer to the OFDM block 154. After step180 the process may proceed to end step 188.

Returning to step 178, when the processor 156 determines that cellulardata may not be sent via the OFDM block 154, that is, collaboration maynot be implemented, the process may proceed to step 182. In step 182,when the processor 156 determines that OFDM data may be sent via thecellular block 152, that is, collaboration may be implemented, theprocess may proceed to step 184. In step 184, the OFDM data may betransferred to the cellular block 152 from the OFDM block 154 via thecommon bus 160. In this regard, the OFDM data may be first stored in thememory 158 before final transfer to the cellular block 152. After step184 the process may proceed to end step 188.

Returning to step 182, when the processor 156 determines that OFDM datamay not be sent via the cellular block 152, that is, collaboration maynot be implemented, the process may proceed to step 186. In step 186,the cellular data may be sent via the cellular block 152 and/or the OFDMdata may be sent via the OFDM block 154 in accordance with thecommunication rates that may be supported by each of those blocks. Inthis regard, when collaboration may not be implemented, the cellularcommunication and the OFDM-based communication of the mobile terminal150 may each be limited by their corresponding communication links.

FIG. 1C is a block diagram illustrating an exemplary reconfigurable OFDMchip with single channel weight diversity, in accordance with anembodiment of the invention. Referring to FIG. 1C, there is shown areconfigurable OFDM block 190 that may comprise a transmit path 191 aand a receive path 191 b. The reconfigurable OFDM block 190 may beadapted to support single weight diversity in the transmit path 191 aand/or in the receive path 191 b, for example. The transmit path 191 amay comprise an outer coder 192 a, an inner coder 193 a, a mapper 194 a,a pilot and transmission parameter signaling (TPS) insertion block 195a, an inverse FFT (IFFT) 196 a, a guard interval insertion block 197 a,and a radio frequency (RF) modulation block 198 a. The receive path 191b may comprise an RF modulation block 198 b, a guard interval removalblock 197 b, an FFT 196 b, a pilot and TPS removal block 195 b, ademapper 194 b, an inner decoder 193 b, and an outer decoder 192 b.

The outer coder 192 a may comprise suitable logic, circuitry, and/orcode that may be adapted to provide a first encoding of the data to betransmitted. For example, the outer coder 192 a may be adapted toperform a Reed-Solomon error correction encoding operation. In thisregard, the outer coder 192 a may be utilized to implement forward errorcorrection (FEC) operations, for example, where such FEC operations ofthe outer coder 192 a may be configurable. The inner coder 193 a maycomprise suitable logic, circuitry, and/or code that may be adapted toprovide a second encoding of the data to be transmitted. For example,the inner coder 193 a may be adapted to perform a convolutional code onthe output of the outer coder 192 a. When the inner coder 193 a isimplemented utilizing a convolutional encoder, the convolutional encodermay be configured to an encoding rate of R=½, and an encoder's lengthconstraint ranging between K=7 and K=9, for example. When the outercoder 192 a is implemented utilizing a puncturer, the rates of thepuncturer may be configured to ⅔, ¾, or ⅚, for example. A puncturer maybe utilized to periodically delete selected bits to reduce codingoverhead. In some instances, the outer coder 192 a may be implementedusing an interleaver, for example. When appropriate, the encoding rate,the encoder's length constraint, the interleaver, and/or the puncturerrate of the inner coder 193 a may be configurable.

The mapper 194 a may comprise suitable logic, circuitry, and/or codethat may be adapted to map the output of the inner coder 193 a to aspecified modulation constellation. For example, the mapper 194 a may beadapted to perform X-QAM, where X indicates the size of theconstellation to be used for quadrature amplitude modulation. The mapper194 a may be configured to map the output of the inner coder 193 a toquadrature phase shift keying (QPSK), binary phase shift keying (BPSK),16-QAM, or 64-QAM, for example. Moreover, the mapping performed by themapper 194 a may result in an in-phase (I) data stream and a phasequadrature (Q) data stream.

The pilot and TPS insertion block 195 a may comprise suitable logic,circuitry, and/or code that may be adapted to insert OFDM pilot signalsand/or transmission parameters signals into the I and Q data streams.The IFFT 196 a may comprise suitable logic, circuitry, and/or code thatmay be adapted to perform an inverse FFT operation of the output of thepilot and TPS insertion block 195 a. In this regard, the number ofpoints to be used by the IFFT 196 a may be configurable and may bemodified in accordance with the OFDM configuration mode selected. TheIFFT 196 a may have a range from 64 points to 8K points, for example.The IFFT 196 a may be implemented as a one-dimensional IFFT for data,text, and/or audio applications, and may be implemented as atwo-dimensional IFFT for images and/or video applications, for example.The guard interval insertion block 197 a may comprise suitable logic,circuitry, and/or code that may be adapted to insert a guard intervalinto the contents of the I and Q data streams. The time intervalinserted by the guard interval insertion block 197 a may beconfigurable. For example, the time interval inserted may range between400 ns and 800 ns.

The RF modulation block 198 a may comprise suitable logic, circuitry,and/or code that may be adapted to modulate the output of the guardinterval insertion block 197 a in accordance with the OFDM configurationmode. In this regard, the operating bandwidth of the RF modulation block198 a may be configurable. The operating bandwidth may range between 20MHz and 80 Mhz, for example. When the RF modulation block 198 a supportssingle weight diversity, channel weights to be applied to at least oneof the R transmit antennas 155 a (Tx_(—)0), . . . , 155 b (Tx_R−1) maybe generated by the RF modulation block 198 a. The RF modulation block198 a may then transmit weighted signals via the R transmit antennas 155a (Tx_(—)0), . . . , 155 b (Tx_R−1).

The RF demodulation block 198 b may comprise suitable logic, circuitry,and/or code that may be adapted to demodulate the input signals receivedvia the P receive antennas 155 c (Rx_(—)0), . . . , 155d (Rx_P−1). Forexample, the operating bandwidth of the RF demodulation block 198 b maybe configurable. In this regard, the operating bandwidth may rangebetween 20 MHz and 80 Mhz, for example. When the RF demodulation block198 b supports single weight diversity, channel weights to be applied toat least one of the P receive antennas 155 c (Rx_(—)0), . . . , 155 d(Rx_P−1) may be generated by the RF demodulation block 198 b. The RFmodulation block 198 b may then transfer the I and Q data streamsgenerated from a combination of the weighted received signals to theguard interval removal block 187 b. The weight generation in the RFdemodulation block 198 b may be configurable. For example, channelestimation operations for weight generation may be configured in aper-tone estimation basis.

The guard interval removal block 197 b may comprise suitable logic,circuitry, and/or code that may be adapted to remove a guard intervalintroduced into the contents of the I and Q data streams. The timeinterval removal by the guard interval removal block 197 a may beconfigurable. For example, the time interval removal may range between400 ns and 800 ns and may be selected in accordance with the OFDMconfiguration mode.

The FFT 196 b may comprise suitable logic, circuitry, and/or code thatmay be adapted to perform an FFT operation of the output of the guardinterval removal block 197 b. In this regard, the number of points to beused by the FFT 196 b may be configurable and may be modified inaccordance with the OFDM configuration mode selected. The FFT 196 b mayhave a range from 64 points to 8K points, for example. The FFT 196 b maybe implemented as a one-dimensional FFT for data, text, and/or audioapplications, and may be implemented as a two-dimensional FFT for imagesand/or video applications, for example. The pilot and TPS removal block195 b may comprise suitable logic, circuitry, and/or code that may beadapted to remove OFDM pilot signals and/or transmission parameterssignals inserted into the I and Q data streams.

The demapper 194 b may comprise suitable logic, circuitry, and/or codethat may be adapted to reverse the mapping of the I and Q data streamsfrom the pilot and TPS removal block 195 b. The demapper 194 b may beconfigured to reverse map QPSK, BPSK, 16-QAM, or 64-QAM, for example.Moreover, the reverse mapping performed by the demapper 194 b may resultin a combined data stream from the I and Q data streams from the pilotand TPS removal block 195 b.

The inner decoder 193 b may comprise suitable logic, circuitry, and/orcode that may be adapted to provide a first decoding of the datareceived. For example, the inner decoder 193 b may be adapted to performa Viterbi decoding on the output of the demapper 194 b. Whenappropriate, the decoding rate, the decoder's length constraint, and/orthe puncturer rate of the inner decoder 193 ba may be configurable.

The outer decoder 192 b may comprise suitable logic, circuitry, and/orcode that may be adapted to provide a second decoding of the data to bereceived. For example, the outer decoder 192 b may be adapted to performa Reed-Solomon error correction decoding operation. In this regard, theouter decoder 192 a FEC operations may be configurable. The output ofthe outer decoder 192 b is the signal or data received.

The configurable portions of the reconfigurable OFDM block 190 in FIG.1C may be programmed via the plurality of registers 157 in FIG. 1A. Inthis regard, the processor 156 may generate at least one signal totransfer the appropriate values to be utilized by the configurableportions of the reconfigurable OFDM block 190 from the memory 158 to theplurality of registers 157.

During transmission operation, the processor 156 may generate at leastone signal to program portions of the transmit path 191 a and portionsof the receive path 191 b in accordance with a selected OFDMconfiguration mode. Data to be transmitted may be first encoded by theouter coder 192 a and then by the inner coder 193 a. The output of theinner coder 193 a may be mapped in the mapper 194 a to the configuredconstellation to generate I and Q data streams. The pilot and TPSinsertion block 195 a may insert signals into the I and Q data streamsgenerated by the mapper 194 a. The IFFT 196 a may operate on the outputof the pilot and TPS insertion block 195 a in accordance with theconfigured number of points and may transfer the results to the guardinterval insertion block 197 a. The guard interval insertion block 197 amay insert a configured time interval into the contents of the I and Qdata streams and may transfer the results to the RF modulation block 198a. The RF modulation block 198 a may modulate the signals received fromthe guard interval insertion block 197 a. The RF modulation block 198 a,when supporting single weight diversity, may generate channel weightsthat may be utilized to generate a plurality of signals to betransmitted via the R transmit antennas 155 a (Tx_(—)0), . . . , 155 b(Tx_R−1).

During reception operation, signals may be received by the P receiveantennas 155 d (Rx_(—)0), . . . , 155 d (Rx_P−1). When supporting singleweight diversity, the RF demodulation block 198 b may generate channelweights to modify the received signals. A single received signal for RFdemodulation may be generated by combining the weighted receivedsignals. The RF demodulation block 198 b may generate I and Q datastreams by demodulating the single received signal generated. The guardinterval removal block 197 b may remove a configured time interval fromthe contents of the I and Q data streams and may transfer the results tothe FFT 196 b. The FFT 196 b may operate on the output of the guardinterval removal block 197 b in accordance with the configured number ofpoints and may transfer the results to the pilot and TPS removal block195 b. The pilot and TPS removal block 195 b may remove signals insertedinto the I and Q data streams and may transfer the results to thedemapper 194 b. The demapper 194 b may reverse map the I and Q datastreams outputs from the pilot and TPS removal block 195 b into a singledata stream in accordance with the configuration provided. The innerdecoder 193 b may decode the data stream from the demapper 195 b and theouter decoder 192 b may decode the data stream from the inner decoder193 b. In this regard, the inner decoder 193 b and the outer decoder 192b may perform decoding operations that correspond to the encodingoperations performed by the inner coder 193 a and the outer coder 192 arespectively. The output of the outer decoder 192 b may correspond tothe received data.

U.S. application Ser. No. 11/237,002 and U.S. application Ser. No.11/237,045 provide a detailed description of a configurable OFDM blockand are hereby incorporated herein by reference in their entirety.

FIG. 2A is a block diagram of an exemplary two-transmit (2-Tx) andtwo-receive (2-Rx) antennas wireless communication system with receiverchannel estimation, in accordance with an embodiment of the invention.Referring to FIG. 2A, the wireless communication system 200 may comprisea transmitter 226, a first transmit antenna (Tx_(—)1) 238, an additionaltransmit antenna (Tx_(—)2) 240, a first receive antenna (Rx_(—)1) 206,and an additional receive antenna (Rx_(—)2) 208. The wirelesscommunication system 200 may further comprise a mixer 210, an adder 212,an RF block 214, a filter 216, a baseband (BB) processor 220, a singleweight baseband generator (SWBBG) 221, a single weight generator (SWG)channel estimator 222, and a SWG algorithm block 224.

The transmitter 226 may comprise suitable logic, circuitry, and/or codethat may be adapted to process single channel (SC) communication signalsfor transmission utilizing OFDM modulation techniques. The transmitter226 may also be adapted to receive feedback from a wireless receiver viaa feedback link 202. The transmitter 226 may be adapted to transmitsignals via the first transmit antenna (Tx_(—)1) 238 and the additionaltransmit antenna (Tx_(—)2) 240. The first transmit antenna, Tx_(—)1 238,and the additional or second transmit antenna, Tx_(—)2 240, may comprisesuitable hardware that may be adapted to transmit a plurality of SCcommunication signals, s_(T) from the transmitter 226. The first receiveantenna, Rx_(—)1 206, and the additional or second receive antenna,Rx_(—)2 208, may comprise suitable hardware that may be adapted toreceive at least a portion of the transmitted SC communication signalsin a wireless receiver device. For example, the receive antenna Rx_(—)1206 may receive signal s_(R1) while the receive antenna Rx_(—)2 208 mayreceive signal s_(R2). The propagation channels that corresponds to thepaths taken by the SC communication signals transmitted from thetransmit antennas Tx_(—)1 238 and Tx_(—)2 240 and received by thereceive antenna Rx_(—)1 206 may be represented by h₁₁ and h₁₂respectively. In this regard, h₁₁ and h₁₂ may represent the actual timevarying impulse responses of the radio frequency (RF) paths taken by theSC communication signals transmitted from the transmit antennas Tx_(—)1238 and Tx_(—)2 240 and received by the receive antenna Rx_(—)1 206.

Similarly, the propagation channels that corresponds to the paths takenby the SC communication signals transmitted from the transmit antennasTx_(—)1 238 and Tx_(—)2 240 and received by the receive antenna Rx_(—)2208 may be represented by h₂₁ and h₂₂ respectively. In this regard, h₂₁and h₂₂ may represent the actual time varying impulse responses of theRF paths taken by the SC communication signals transmitted from thetransmit antennas Tx_(—)1 238 and Tx_(—)2 240 and received by thereceive antenna Rx_(—)2 208. In some instances, a wireless transmitterdevice comprising a single transmit antenna may be adapted toperiodically transmit calibration and/or pilot signal that may beutilized by a 2-Rx antennas wireless receiver device to determineestimates of h₁₁, h₁₂, h₂₁, and h₂₂. The 2-Tx and 2-Rx antennas wirelesscommunication system 200 in FIG. 2A may represent a MIMO communicationsystem whereby the diversity gain may be increased for the transmitteddata.

The mixer 210 may comprise suitable logic and/or circuitry that may beadapted to operate as a complex multiplier that may modify the amplitudeand/or phase of the portion of the SC communication signals received bythe receive antenna Rx_(—)2 208 via a rotation waveform e^(jw) ^(r) ^(t)provided by the SWBBG 121, where w_(r)2πf_(r) and f_(r) is the rotationfrequency. In this regard, a channel weight comprising an amplitudecomponent and phase component may be provided by the SWBBG 221 formodifying the signal received by the receive antenna Rx_(—)2 208 toachieve channel orthogonality between the receive antenna Rx_(—)1 206and the receive antenna Rx_(—)2 208. In some implementations, the mixer210 may comprise an amplifier and a phase shifter, for example.

Through the achieved channel orthogonality, estimates of h₁₁, h₁₂, h₂₁,and h₂₂ may be determined by the SWG channel estimator 222 in the SWBBG221. The h₁₁, h₁₂, h₂₁, and h₂₂ estimates may be utilized by the SWGalgorithm block 224 to determine an optimum amplitude A and phase φ thatmodify signals received by the receive antenna Rx_(—)2 208 via mixer 210so that the receiver signal-to-interference-and-noise ratio (SINR) ismaximized. In some instances, instead of utilizing the rotation waveforme^(jw) ^(r) ^(t) to achieve the channel orthogonality between thereceive antenna Rx_(—)1 106 and the receive antenna Rx_(—)2 108, squareor triangular waveforms may be also utilized. Moreover, waveformsrepresenting different orthogonal codes may also be utilized.

In some instances, the output of the mixer 210 may be transferred to abandpass filter, a low noise amplifier (LNA), and/or a phase shifter forfurther processing of the received signals. The adder 212 may comprisesuitable hardware, logic, and/or circuitry that may be adapted to addthe output of the receive antenna Rx_(—)1 206 and the output of themixer 210 to generate a combined received SC communication signal,s_(RC). In some instances, bringing the output signals of the receiveantenna Rx_(—)1 206 and the mixer 210 together into a single electricalconnection may provide the functionality of the adder 212.Notwithstanding, an output of the adder 212 may be transferred to the RFblock 214 for further processing of the combined received SCcommunication signal, s_(RC).

The RF block 214 may comprise suitable logic and/or circuitry that maybe adapted to process the combined received SC communication signal,s_(RC). The RF block 214 may perform, for example, filtering,amplification, and/or analog-to-digital (A/D) conversion operations. TheBB processor 220 may comprise suitable logic, circuitry, and/or codethat may be adapted to determine a first baseband combined channelestimate, ĥ₁, which may comprise information regarding propagationchannels h₁₁ and h₂₁. The BB processor 220 may also be adapted toprocess the output of the RF block 214 to determine a second basebandcombined channel estimate, ĥ₂, which may comprise information regardingpropagation channels h₁₂ and h₂₂. The BB processor 220 may also beadapted to determine an estimate of the transmitted SC communicationsignals, ŝ_(T). The filter 216 may comprise suitable logic, circuitry,and/or code that may be adapted to limit the bandwidth of the digitaloutput from the RF block 214. The output of the filter 216 may betransferred, for example, to the BB processor 220 for furtherprocessing.

The SWBBG 221 may comprise suitable logic, circuitry, and/or code thatmay be adapted to receive the first and second baseband combined channelestimates, ĥ₁ and ĥ₂, from the BB processor 220 and generate phase andamplitude components of the rotation waveform to be applied by the mixer210 to modify the portion of the SC communication signals received bythe receive antenna Rx_(—)2 208, s_(R2). The SWG channel estimator 222may comprise suitable logic, circuitry, and/or code that may be adaptedto process the first and second baseband combined channel estimates, ĥ₁and ĥ₂, generated by the BB processor 220 and may determine a matrixĤ_(2×2) of propagation channel estimates ĥ₁₁, ĥ₁₂, ĥ₂₁, and ĥ₂₂, whichcorrespond to estimates of a matrix H_(2×2) of time varying impulseresponses h₁₁, h₁₂, h₂₁, and h₂₂ respectively. The SWG algorithm block224 may comprise suitable logic, circuitry, and/or code that may beadapted to determine a channel weight to be transferred to the mixer 210to modify the signal s_(R2) so that the receiver SINR is maximized. Thechannel weight to be transferred to the mixer 210 may refer to a phase,φ, and amplitude, A, that results in a maximum SINR. Moreover, the SWGalgorithm block 224 may be adapted to generate feedback factors to thetransmitter 226 jointly and/or concurrently with the channel weight forthe mixer 210.

FIG. 2B is a block diagram of an exemplary two-transmit (2-Tx) andmultiple-receive (M-Rx) antennas wireless communication system withreceiver channel estimation, in accordance with an embodiment of theinvention. Referring to FIG. 2B, the wireless communication system 250may differ from the wireless communication system 200 in FIG. 2A in that(M−1) additional receive antennas Rx_(—)2 208 to Rx_M 209, and (M−1)mixers 210 to 211 may be utilized, where M is the total number ofreceive antennas in the wireless receiver.

The propagation channels that correspond to the paths taken by the SCcommunication signals transmitted from the transmit antennas Tx_(—)1 238and Tx_(—)2 240 and received by the receive antennas Rx_(—)1 206 to Rx_M209 may be represented by an M×2 matrix, H_(M×2). The matrix H_(M×2) maycomprise propagation channels h₁₁ to h_(M1) and H₁₂ to h_(M2). In thisregard, h₁₁ to h_(M1) may represent the time varying impulse responsesof the RF paths taken by the portion of the transmitted SC communicationsignals transmitted by transmit antenna Tx_(—)1 238 and received by thereceive antennas Rx_(—)1 206 to Rx_M 209 respectively. Similarly, h₁₂ toh_(M2) may represent the time varying impulse responses of the RF pathstaken by the portion of the transmitted SC communication signalstransmitted by transmit antenna Tx_(—)2 240 and received by the receiveantennas Rx_(—)1 206 to Rx_M 209 respectively. In some instances, awireless transmitter device comprising a first and a second transmitantenna may be adapted to periodically transmit calibration and/or pilotsignals that may be utilized by an M-Rx antenna wireless receiver deviceto determine estimates of h₁₁ to h_(M1) and h₁₂ to h_(M2). The 2-Tx andM-Rx antennas wireless communication system 250 in FIG. 2B may representa MIMO communication system whereby the diversity gain may be increasedfor the transmitted data.

The mixers 210 to 211 may comprise suitable logic and/or circuitry thatmay be adapted to operate as a complex multiplier that may modify thephase of the portion of the SC communication signals received by thereceive antennas Rx_(—)2 208 to Rx_M 209 via a rotation waveforms e^(jw)^(r1) ^(t) to e^(jw) ^(r(M−1)) ^(t), where w_(rk)=2πf_(rk) and f_(rk) isthe rotation frequency that preserves the orthogonality of the receivedsignals at the multiple receiving antennas Rx_(—)1 206 to Rx_M 209. Therotation frequency that preserves the signal orthogonality at thereceiving antennas may be selected as f_(rk)=kf_(r) where k=1,2, 3, . .. , M−1. Other rotation waveforms such as triangular or square waveformsmay be utilized with the same frequency relationships. In addition,waveforms representing different orthogonal codes of the same frequencymay be utilized. In this regard, the following exemplary sequences maybe utilized: the first receive antenna Rx_(—)1 206 may utilize thesequence [1 1 1 1], the second receive antenna Rx_(—)2 208 may utilizethe sequence [−1 −1 1 1], a third receive antenna (Rx_(—)3) may utilizethe sequence [−1 1 −1 1], and so on. In this embodiment, e^(jw) rk ^(t)is used as an exemplary waveform.

The channel weights comprising phase components for the rotationwaveforms may be provided by the SWBBG 221 for modifying the signalsreceived by the receive antennas Rx_(—)2 208 to Rx_M 209 to achievechannel orthogonality between the receive antenna Rx_(—)1 206 and thereceive antennas Rx_(—)2 208 to Rx_M 209. In some instances, the outputof the mixers 210 to 211 may be transferred to a bandpass filter and/ora low noise amplifier (LNA) for further processing of the receivedsignals. The adder 212 may comprise suitable hardware, logic, and/orcircuitry that may be adapted to add the output of the receive antennaRx_(—)1 206 with the output of the mixers 210 to 211 to generate acombined received SC communication signal, s_(RC), or gain balancedpoint. In some instances, bringing the output signals of the receiveantenna Rx_(—)1 206 and the mixers 210 to 211 together into a singleelectrical connection may provide the functionality of the adder 212.Notwithstanding, an output of the adder 212 may be transferred to the RFblock 214 tor further processing of the combined received SCcommunication signal, s_(RC).

The BB processor 220 in FIG. 2B may be adapted to determine a firstbaseband combined channel estimate, ĥ₁, which may comprise informationregarding propagation channels h₁₁ to h_(M1). For example, a portion ofĥ₁ may comprise information regarding the propagation channels betweenthe transmit antenna Tx_(—)1 238 and the receive antennas Rx_(—)1 206and Rx_(—)2 208, that is, h₁₁ and h₂₁, while another portion of ĥ₁ maycomprise information regarding the propagation channels between thetransmit antenna Tx_(—)1 238 and the receive antennas Rx_(—)1 206 andRx_M 209, that is, h₁₁ and h_(M1). The actual time varying impulseresponses h₁₁ to h_(M1) may comprise multiple propagation paths arrivingat different time delays.

The BB processor 220 in FIG. 2B may also be adapted to determine asecond baseband combined channel estimate, ĥ₂, which may compriseinformation regarding propagation channels h₁₂ to h_(M2). For example, aportion of ĥ₂ may comprise information regarding the propagationchannels between the transmit antenna Tx_(—)2 240 and the receiveantennas Rx_(—)1 206 and Rx_(—)2 208, that is, h₁₂ and h₂₂, whileanother portion of ĥ₂ may comprise information regarding the propagationchannels between the transmit antenna Tx_(—)2 240 and the receiveantennas Rx_(—)1 206 and Rx_M 209, that is, h₁₂ and h_(M2). The actualtime varying impulse responses h₁₂ to h_(M2) may comprise multiplepropagation paths arriving at different time delays. The combinedchannel estimates may be determined, that is, may be separated, in theBB processor 220 utilizing the orthogonality of the received signals,for example.

The SWG channel estimator 222 in FIG. 2B may be adapted to process thefirst and second baseband combined channel estimates, ĥ₁ and ĥ₂,determined by the BB processor 220 and may determine a matrix Ĥ_(M×2) ofpropagation channel estimates ĥ₁₁ to ĥ_(M1) and ĥ₁₂ to ĥ_(M2), whichcorrespond to estimates of the matrix H_(M×2) of time varying impulseresponses h₁₁ to h_(M1) and h₁₂ to h_(M2), respectively. The SWGalgorithm block 224 may utilize the contents of the matrix Ĥ_(M×2) todetermine (M−1) channel weights to be applied to the mixers 210 to 211to modify the portions of the transmitted SC communication signalsreceived by the additional receive antennas Rx_(—)2 208 to Rx_M 209 sothat the receiver SINR is maximized, for example. The (M−1) channelweights may comprise amplitude and phase components, A₁ to A_(M−1) andφ₁ to Φ_(M−1), for example. Moreover, the SWG algorithm block 224 may beadapted to generate feedback information jointly and/or concurrentlywith the (M−1) channel weights.

FIG. 3A is a flow diagram illustrating exemplary steps for channelestimation in a 2-Tx and M-Rx antennas wireless communication system, inaccordance with an embodiment of the invention. Referring to FIG. 3A,after start step 302, in step 304, the SC communication signals, s_(T),may be transmitted from the transmit antennas Tx_(—)1 238 and Tx_(—)2240 in FIG. 2B. In step 306, the first and additional receive antennas,R_(—)1 206 to Rx_M 209, may receive a portion of the transmitted SCcommunication signals. In step 308, the signals received by theadditional receive antennas Rx_(—)1 206 to Rx_M 209 may be multipliedby, for example, rotation waveforms, such as sine, square, or triangularwaveforms for example, in the mixers 210 to 211 in FIG. 2B. In thisregard, the rotation waveforms may have a given set of amplitude andphase component values. In step 310, the output of the receive antennaRx_(—)1 206 and the output of the mixers 210 to 211 associated with theadditional receive antennas Rx_(—)2 208 to Rx_M 209 may be added orcombined into the received SC communication signal, s_(RC). Thecombination may occur in the adder 212, for example.

In step 312, the BB processor 220 may determine the first and secondbaseband combined channel estimates, ĥ₁ and ĥ₂, which compriseinformation regarding propagation channels h₁₁ to h_(M1) and h₁₂ toh_(M2). In step 314, the SWG channel estimator 222 in the SWBBG 221 maydetermine the matrix Ĥ_(M×2) of propagation channel estimates ĥ₁₁ toĥ_(M1) and ĥ₁₂ to ĥ_(M2). In this regard, the propagation channelestimates ĥ₁₁ to ĥ_(M1) and ĥ₁₂ to ĥ_(M2) may be determinedconcurrently.

In step 316, the (M−1) maximum SNIR channel weights that compriseamplitude and phase components, A₁ to A_(M−1) and φ₁ to φ_(M−1), may begenerated concurrently. The feedback information provided to thetransmitter 226 may be generated concurrently with the (M−1) maximumSNIR channel weights. In step 318, additional SC communication signalsreceived may be phase and amplitude adjusted based on the maximum SNIRchannel weights applied to the mixers 210 to 211. The channel estimationphase rotation and the maximum SINR phase/amplitude adjustment describedin flow chart 300 may be performed continuously or may be performedperiodically. In this regard, FIG. 3B illustrates an exemplary periodicphase rotation for an in-phase (I) signal 330 received in one of theadditional receive antennas, in accordance with an embodiment of theinvention. Aspects of single weight diversity operations and/orimplementations as described in FIGS. 2A-3B may also be utilized in thereconfigurable OFDM block 190 in FIG. 1C.

FIG. 4A is a block diagram of an exemplary single weight basebandgenerator (SWBBG) that may be utilized in a 2-Tx and 2-Rx antennassystem, in accordance with an embodiment of the invention. Referring toFIG. 4A, a receiver system 400 may comprise a first receive antenna(Rx_(—)1) 402, an addiiional receive antenna (Rx_(—)2) 404, an adder406, a mixer 408, and a single weight baseband generator (SWBBG) 410.The SWBBG 410 may comprise a phase rotator start controller 414, a delayblock 416, a single weight generator (SWG) channel estimator 418, an SWGalgorithm block 420, and an RF phase and amplitude controller 412. TheSWBBG 410 may represent an exemplary implementation of the SWBBG 221 inFIG. 2B. At least some of the various portions of the receiver system400 in FIG. 4A may be implemented in the reconfigurable OFDM block 190in FIG. 1C to support single weight diversity, for example.

The first receive antenna, Rx_(—)1 402, and the additional or secondreceive antenna, Rx_(—)2 404, may comprise suitable hardware that may beadapted to receive at least a portion of transmitted SC communicationsignals in the receiver system 400. For example, the receive antennaRx_(—)1 402 may receive a signal s_(R1) while the receive antennaRx_(—)2 404 may receive a signal s_(R2). The mixer 408 may correspondto, for example, the mixer 210 in FIG. 2B. In some instances, the outputof the mixer 308 may be communicated to a bandpass filter and/or a lownoise amplifier (LNA) for further processing of the received signals.

The adder 406 may comprise suitable hardware, logic, and/or circuitrythat may be adapted to add the output of the receive antenna Rx_(—)1 402and the output of the mixer 408 to generate a combined received SCcommunication signal, s_(RC). In some instances, bringing the outputsignals of the receive antenna Rx_(—)1 402 and the mixer 408 togetherinto a single electrical connection may provide the functionality of theadder 406. The output of the adder 406 may be transferred to additionalprocessing blocks for RF and baseband processing of the combinedreceived SC communication signal, s_(RC).

The phase rotator and start controller 414 may comprise suitable logic,circuitry, and/or code that may be adapted to control portions of theoperation of the RF phase and amplitude controller 412 and to controlthe delay block 416. The phase rotator and start controller 414 mayreceive a signal, such as a reset signal, from, for example, the BBprocessor 220 in FIG. 2B, or from firmware operating in a processor, toindicate the start of operations that determine the propagation channelestimates and/or the channel weight to apply to the mixer 408. The delayblock 416 may comprise suitable logic, circuitry, and/or code that maybe adapted to provide a time delay to compensate for the RF/modem delay.The delay may be applied in order to compensate for the interval of timethat may occur between receiving the combined channel estimates, ĥ₁ andĥ₂, modified by the rotation waveform and the actual rotating waveformat the mixer 408.

The SWG channel estimator 418 may comprise suitable logic, circuitry,and/or code that may be adapted to process the first and second basebandcombined channel estimates, ĥ₁ and ĥ₂, and determine the matrix Ĥ_(2×2)of propagation channel estimates ĥ₁₁, ĥ₁₂, ĥ₂₁, and ĥ₂₂. The SWG channelestimator 418 may also be adapted to generate an algorithm start signalto the SWG algorithm block 420 to indicate that the propagation channelestimates ĥ₁₁, ĥ₁₂, ĥ₂₁, and ĥ₂₂ are available for processing. In thisregard, the algorithm start signal may be asserted when integrationoperations performed by the SWG channel estimator 418 have completed.

The SWG algorithm block 420 may comprise suitable logic, circuitry,and/or code that may be adapted to determine a channel weight to betransferred to the mixer 408 via the RF phase and amplitude controller412 to modify the signal s_(R2). The channel weight to be transferred tothe mixer 408 may refer to the phase, φ, and amplitude, A. The channelweight may be based on the propagation channel estimatesĥ₁₁, ĥ₁₂, ĥ₂₁,and ĥ₂₂ and on additional information such as noise power estimates andinterference propagation channel estimates, for example. The SWGalgorithm block 420 may also be adapted to generate an algorithm endsignal to indicate to the RF phase and amplitude controller 412 that thechannel weight has been determined and that it may be applied to themixer 408. The SWG algorithm block 420 in FIG. 4A may also be adapted todetermine the feedback information that may be transferred to thetransmitter 226 in FIG. 2A. The feedback information may be calculatedjointly to maximize the receiver SINR, for example.

The RF phase and amplitude controller 412 may comprise suitable logic,circuitry, and/or code that may be adapted to apply the rotationwaveform e^(jw) ^(r) ^(t) to the mixer 408. When phase and amplitudecomponents, A and φ, that correspond to the channel weight determined bythe SWG algorithm block 420 are available, the RF phase and amplitudecontroller 412 may apply amplitude A and phase φ to the mixer 408. Inthis regard, the RF phase and amplitude controller 412 may apply therotation waveform or the amplitude and phase components in accordancewith the control signals provided by the phase rotator start controller414 and/or the algorithm end signal generated by the SWG algorithm block420.

The phase rotation operation performed on the s_(R2) signal in theadditional receive antenna Rx_(—)2 404 may be continuous or periodic. Acontinuous rotation of the s_(R2) signal may be perceived by a wirelessmodem as a high Doppler, and for some modem implementations this maydecrease the modem's performance. When a periodic rotation operation isutilized instead, the period between consecutive phase rotations maydepend on the Doppler frequency perceived by the wireless modem. Forexample, in a higher Doppler operation, it may be necessary to performmore frequent channel estimation while in a lower Doppler operation,channel estimation may be less frequent. The signal rotation period mayalso depend on the desired wireless modem performance and the accuracyof the propagation channel estimation. For example, when the Dopplerfrequency is 5 Hz, the period between consecutive rotations may be 1/50sec, that is, 10 rotations or channel estimations per signal fade.

FIG. 4B is a block diagram of an exemplary single weight basebandgenerator (SWBBG) that may be utilized in a 2-Tx and M-Rx antennassystem, in accordance with an embodiment of the invention. Referring toFIG. 4B, a receiver system 430 may differ from the receiver system 400in FIG. 4A in that (M−1) additional receive antennas, Rx_(—)2 404 toRx_M 405, and (M−1) mixers 408 to 409 may be utilized. In this regard,the SWG channel estimator 418 may be adapted to process the first andsecond baseband combined channel estimates, ĥ₁ and ĥ₂, and determine thematrix Ĥ_(M×2) of propagation channel estimates ĥ₁₁ to ĥ_(M1) and ĥ₁₂ toĥ_(M2). At least some of the various portions of the receiver system 430may be implemented in the reconfigurable OFDM block 190 in FIG. 1C tosupport single weight diversity, for example.

The SWG algorithm block 420 may also be adapted to determine (M−1)channel weights, that may be utilized to maximize receiver SINR, forexample, to be applied to the mixers 408 to 409 to modify the portionsof the transmitted SC communication signals received by the additionalreceive antennas Rx_(—)2 404 to Rx_M 405. The (M−1) channel weights maycomprise amplitude and phase components, A₁ to A_(M−1) and φ₁ toφ_(M−1). The SWG algorithm block 420 in FIG. 4B may also be adapted todetermine the feedback information that may be transferred to thetransmitter 226 in FIG. 2A. The channel weights and the feedbackinformation may be calculated jointly to maximize the receiver SINR, forexample.

The RF phase and amplitude controller 412 may also be adapted to applyrotation waveforms e^(jw) ^(r1) ^(t) to e^(jw) ^(r(M−1)) ^(t) or phaseand amplitude components, A₁ to A_(M−1) and φ₁ to φ_(M−1), to the mixers408 to 409. In this regard, the RF phase and amplitude controller 312may apply the rotation waveforms or the amplitude and phase componentsin accordance with the control signals provided by the phase rotatorstart controller 414 and/or the algorithm end signal generated by theSWG algorithm block 420.

FIG. 4C is a block diagram of an exemplary RF phase and amplitudecontroller, in accordance with an embodiment of the invention. Referringto FIG. 4C, the RF phase and amplitude controller 412 may comprise aswitch 440, a plurality of rotation waveform sources 442, and aplurality of SWG algorithm weights 444. The switch 440 may comprisesuitable hardware, logic, and/or circuitry that may be adapted to selectbetween the rotation waveforms e^(jw) ^(r1) ^(t) to e^(jw) ^(r(M−1))^(t) and the SWG algorithm determined weights A₁e^(jφ) ¹ toA_(M−1)e^(jφ) ^(M−1) . The rotation waveform sources 442 may comprisesuitable hardware, logic and/or circuitry that may be adapted togenerate the signal e^(jw) ^(rk) ^(t), where w_(rk)=2πf_(rk) and f_(rk)is the rotation frequency that preserves the orthogonality of thereceived signals at the receive antennas Rx_(—)2 402 to Rx_M 405 in FIG.4B, for example. The rotation frequency that preserves the signalorthogonality at the receiving antennas may be selected as w_(rk)=kw_(r)where k=1, 2, . . . , M−1. Other rotation waveforms such as triangularor square waveforms may be utilized with the same frequencyrelationships. Moreover, waveforms representing different orthogonalcodes of the same frequency may also be utilized. In this embodiment,the signal e^(jw) ^(rk) ^(t) may be utilized as an exemplary waveform.The plurality of SWG algorithm weights 344 may comprise suitablehardware, logic, and/or circuitry that may be adapted to generate thesignals A₁e^(jφ) ¹ to A_(M−1)e^(jφ) ^(M−1) from the amplitude and phasecomponents, A₁ to A_(M−1) and φ₁ to φ_(M−1), respectively.

In operation, the RF phase and amplitude controller 412 may apply thesignals E^(jw) ^(r1) ^(t) to e^(jw) ^(r(M−1)) ^(t) to the mixers 408 to409 in FIG. 4B based on control information provided by the phaserotator start controller 414. The switch 440 may select the rotationwaveform sources 442 based on the control information provided by thephase rotator start controller 414. Once the channel weights aredetermined by the SWG algorithm block 420 and the phase and amplitudecomponents have been transferred to the RF phase and amplitudecontroller 412, the algorithm end signal may be utilized to change theselection of the switch 440. In this regard, the switch 440 may beutilized to select and apply the signals A₁e^(jφ) ¹ to A_(M−1)e^(jφ)^(M−1) to the mixers 408 to 409 in FIG. 4B.

FIG. 5 is a flow diagram illustrating exemplary steps in the operationof the single weight baseband generator (SWBBG) that may be utilized forchannel weight generation in a 2-Tx and M-Rx antennas system, inaccordance with an embodiment of the invention. Referring to FIG. 5,after start step 502, in step 504, the phase rotator start controller414 in FIG. 4B may receive the reset signal to initiate operations fordetermining propagation channel estimates and channel weights in theSWBBG 410. The phase rotator start controller 414 may generate controlsignals to the delay block 416 and to the RF phase and amplitudecontroller 412. The control signals to the delay block 416 may beutilized to determine a delay time to be applied by the delay block 416.The control signals to the RF phase and amplitude controller 412 may beutilized to determine when to apply the rotation waveforms that havebeen modified by the channel weights to the mixers 408 to 409.

In step 506, the RF phase and amplitude controller 412 may applyrotation waveforms, such as those provided by the rotation waveformsources 442 in FIG. 4C, to the mixers 408 to 409 in FIG. 4B. In step508, the delay block 416 may apply a time delay signal to the SWGchannel estimator 418 to reflect the interval of time that may occurbetween receiving the SC communication signals and when the first andsecond baseband combined channel estimates, ĥ₁ and ĥ₂, are available tothe SWG channel estimator 418. For example, the time delay signal may beutilized as an enable signal to the SWG channel estimator 418, where theassertion of the time delay signal initiates operations for determiningpropagation channel estimates. In step 510, the SWG channel estimator418 may process the first and second baseband combined channelestimates, ĥ₁ and ĥ₂, and may determine the matrix Ĥ_(M×2) ofpropagation channel estimates ĥ₁₁ to ĥ_(M1) and ĥ₁₂ to ĥ_(M2). The SWGchannel estimator 418 may transfer the propagation channel estimates ĥ₁₁to ĥ_(M1) and ĥ₁₂ to ĥ_(M2) to the SWG algorithm block 420. In step 512,the SWG channel estimator 418 may generate the algorithm start signaland may assert the signal to indicate to the SWG algorithm block 420that it may initiate operations for determining channel weights.

In step 514, the SWG algorithm block 420 may determine the channelweights comprising phase and amplitude components, A₁ to A_(M−1) and φ₁to φ_(M−1), based on the propagation channel estimates ĥ₁₁ to ĥ_(M1) andĥ₁₂ to ĥ_(M2) and/or noise power estimates, for example. The SWGalgorithm block 420 may transfer the channel weights to the RF phase andamplitude controller 412. In some instances, the SWG algorithm block 420may also generate feedback information. In step 516, the SWG algorithmblock 420 may generate the algorithm end signal to indicate to the RFphase and amplitude controller 412 that the channel weights areavailable to be applied to the mixers 408 to 409. In step 518, the RFphase and amplitude controller 412 may apply the rotation waveforms withphase and amplitude components, A₁ to A_(M−1) and φ₁ to φ_(M−1), to themixers 408 to 409, in accordance with the control signals provided bythe phase rotator start controller 414.

In step 520, the receiver system 430 in FIG. 4B may determine whetherthe phase rotation operation on the received SC communication signals isperiodic. When the phase rotation operation is not periodic butcontinuous, the process may proceed to step 508 where a delay may beapplied to the SWG channel estimator 418. In instances when the phaserotation operation is periodic, the process may proceed to step 522where the receiver system 430 may wait until the next phase rotationoperation is initiated by the reset signal. In this regard, the processcontrol may proceed to step 504 upon assertion of the reset signal tothe phase rotator start controller 414.

FIG. 6 is a block diagram of an exemplary channel estimator for a 2-Txand 2-Rx antennas system, in accordance with an embodiment of theinvention. Referring to FIG. 6, the SWG channel estimator 418 in FIG. 4Autilized in, for example, a 2-Tx and 2-Rx antenna system may comprise afirst channel estimator block 601 and a second channel estimator block603. The first channel estimator block 601 may comprise a phase rotator602, a mixer 606, a first integrator 604, and a second integrator 608.The second channel estimator block 603 may also comprise a phase rotator602, a mixer 606, a first integrator 604, and a second integrator 608.The phase rotator 602 may comprise suitable logic, circuitry, and/orcode that may be adapted to generate a complex conjugate of the rotationwaveform e^(jw) ^(r) ^(t). The first integrator 604 and the secondintegrator 608 may comprise suitable logic, circuitry, and/or code thatmay be adapted to integrate an input signal over a 360-degree phaserotation period.

The accuracy and/or time of the integration may vary and may be selectedby the SWGGB 410 in FIG. 4A. The mixer 606 may comprise suitable logicand/or circuitry that may be adapted to multiply the rotation waveformcomplex conjugate and a baseband combined channel estimate. For example,the mixer 606 in the first channel estimator block 601 and the mixer 606in the second channel estimator block 603 may multiply, respectively,the first and second baseband combined channel estimates, ĥ₁ and ĥ₂,where ĥ₁=ĥ₁₁+e^(jw) ^(r) ^(t)ĥ₂₁ and ĥ₂=ĥ₁₂+e^(jw) ^(r) ^(t)ĥ₂₂, withthe rotation waveform complex conjugate.

In operation, the delay signal from the delay block 416 may indicate tothe phase rotator 602, the first integrator 604, and/or the secondintegrator 608 when to start operations for determining the propagationchannel estimates. After the delay signal is asserted, the secondintegrator 608 may receive the baseband combined channel estimate andmay integrate the baseband combined channel estimate over a 360-degreephase rotation period. The integration time may be selected based onchannel estimation accuracy and required modem performance. A longerintegration time may result in more accurate channel estimates. Thesecond integrator 608 in the first channel estimator block 601 and thesecond integrator 608 in the second channel estimator block 603 maydetermine, respectively, the propagation channel estimates ĥ₁₁ and ĥ₁₂by determining the expectation values of ĥ₁ and ĥ₂ as follows:

ĥ ₁₁ =E[ĥ ₁₁ +e ^(jw) ^(r) ^(t) ĥ ₂₁ ]=ĥ ₁₁ +E[e ^(jw) ^(r) ^(t) ĥ ₂₁],and

ĥ ₁₂ =E[ĥ ₁₂ +e ^(jw) ^(r) ^(t) ĥ ₂₂ ]=ĥ ₁₂ +E[e ^(jw) ^(r) ^(t) ĥ ₂₂],

where E[e^(jw) ^(r) ^(t)ĥ₂₁] and E[e^(jw) ^(r) ^(t)ĥ₂₂] over a full360-degre rotation period are equal to zero. In this regard, channelestimates ĥ₁₁ and ĥ₁₂ may referred to as first channel estimates becausethey correspond to propagation channels related to a first transmitantenna.

After the delay signal is asserted, the first integrator 604 in thefirst channel estimator block 601 and the first integrator 604 in thesecond channel estimator block 603 may receive, respectively, thesignals e^(−jw) ^(r) ^(t)ĥ₁ and e^(−jw) ^(r) ^(t)ĥ₂. The firstintegrator 604 in the first channel estimator block 601 and the firstintegrator 604 in the second channel estimator block 603 may determine,respectively, the channel estimates ĥ₂₁ and ĥ₂₂ by determining theexpectation values of e^(−jw) ^(r) ^(t)ĥ₁ and e^(−jw) ^(r) ^(t)ĥ₂ asfollows:

ĥ ₂₁ =E[e ^(jw) ^(r) ^(t) ĥ ₁ ]=E[e ^(−jw) ^(r) ^(t)(ĥ₁₁ +e ^(jw) ^(r)^(t) ĥ ₂₁)]=E[e ^(−jw) ^(r) ^(t) ĥ ₁₁ +ĥ ₂₁ ]=E[e ^(−jw) ^(r) ^(t) ĥ ₁₁]+ĥ ₂₁, and

ĥ ₂₂ =E[e ^(−jw) ^(r) ^(t) ĥ ₂ ]=E[e ^(−jw) ^(r) ^(t)(ĥ ₁₂ +e ^(jw) ^(r)^(t) ĥ ₂₂)]=E[e ^(−jw) ^(r) ^(t) ĥ ₁₂ +ĥ ₂₂ ]=E[e ^(−jw) ^(r) ^(t) ĥ ₁₂]+ĥ ₂₂

where E[e^(jw) ^(r) ^(t)ĥ₁₁] and E[e^(−jw) ^(r) ^(t)ĥ₁₂] over a full360-degree rotation period is equal to zero. In this regard, channelestimates ĥ₂₁ and ĥ₂₂ may referred to as second channel estimatesbecause they correspond to propagation channels related to a secondtransmit antenna.

The channel estimation operations performed by the SWG channel estimator418 may be extended to cases where M receive antennas result in a firstand second baseband combined channel estimates, ĥ₁ and ĥ₂, whichcomprise information regarding propagation channels h₁₁ to h_(M1) andh₁₂ to h_(M2). In that case, a plurality of channel estimator blocks maybe utilized to determine the matrix Ĥ_(M×2) of propagation channelestimates ĥ₁₁ to ĥ_(M1) and ĥ₁₂ to ĥ_(M2).

FIG. 7 is a flow diagram illustrating exemplary steps for channelestimation based on complex multiplication and integration of a firstand second baseband combined channel estimates, in accordance with anembodiment of the invention. Referring to FIG. 7, after start step 702,in step 704, the integration time and/or integration resolution may beselected for the first and second integrators in FIG. 6. For example,the SWBBG 221 in FIG. 2A may select the integration time. In step 706,the delay signal may be asserted to initiate the operations performed bythe phase rotator 602, the first integrator 604, and the secondintegrator 608. The phase rotator 602 may generate a complex conjugateof the rotation waveform e^(jw) ^(r) ^(t). In step 708, the first andsecond baseband combined channel estimates, ĥ₁ and ĥ₂, may betransferred to the second integrator 608 and to the mixer 606 forprocessing. In step 710, the baseband combined channel estimates, ĥ₁ andĥ₂, may be multiplied by the complex conjugate of the rotation waveforme^(jw) ^(r) ^(t).

In step 712, integration over a 360-degree phase rotation period may beperformed in the first integrator 604 and the second integrator 608 todetermine propagation channel estimates ĥ₂₁ and ĥ₂₂ and ĥ₁₁ and ĥ₂respectively. In step 714, after the propagation channel estimates havebeen determined, the SWG channel estimator 418 in FIG. 4A may generatethe algorithm start signal to indicate to the SWG algorithm block 420that the propagation channel estimates are available. The SWG algorithmblock 420 may start operations for determining channel weights when thealgorithm start signal is asserted. In step 716, the SWG algorithm block420 may generate channel weights based on the propagation channelestimates. The channel weights may be applied to the additional orsecond receive antenna.

In step 718, the receiver system 400 in FIG. 4A may determine whetherthe phase rotation operation on the received SC communication signals isperiodic. When the phase rotation is not periodic but continuous,control may proceed to step 708 where the next set of first and secondbaseband combined channel estimates, ĥ₁ and ĥ₂, from the BB processor220 in FIG. 2A may be available for channel estimation. When the phaserotation is periodic, control may proceed to step 720 where the SWGchannel estimator 418 may wait until the delay signal is asserted toinitiate the operations performed by the phase rotator 602, the firstintegrator 604, and the second integrator 608. In this regard, controlmay proceed to step 706 upon the assertion of the reset signal to thephase rotator start controller 414 and the generation of the controlsignals to the delay block 416.

The channel estimation operations described in FIG. 7 may be extended tocases where M receive antennas result in a first and second basebandcombined channel estimates, ĥ₁ and ĥ₂, which comprise informationregarding propagation channels h₁₁ to h_(M1) and h₁₂ to h_(M2). In thatcase, a plurality of channel estimator blocks may be utilized todetermine the matrix Ĥ_(M×2) of propagation channel estimates ĥ₁₁ toĥ_(M1) and ĥ₁₂ to ĥ_(M2).

In an embodiment of the invention, a machine-readable storage may beprovided, having stored thereon, a computer program having at least onecode section executable by a machine, thereby causing the machine toperform the steps for achieving single weight diversify in areconfigurable orthogonal frequency division multiplexing (OFDM) chip.

Certain aspects of the invention may correspond to a system for handlingwireless communication, the system comprising circuitry within a singlechip that applies at least one of a plurality of channel weightsgenerated within the single chip to at least one of a plurality ofsignals received via a plurality of antennas in a single orthogonalfrequency division multiplexing (OFDM) receiver. One of the signalsreceived may be utilized as a reference signal. Circuitry within thesingle chip may be adapted to combine the signals received via theantennas to generate a single combined received signal. Circuitry withinthe single chip may also be adapted to determine a plurality of channelestimates based on the combined plurality of signals. Circuitry withinthe single chip may also be adapted to determine at least one of aplurality of subsequent channel weights based on the determined channelestimates.

The system may also comprise a processor coupled to the single chip,wherein the processor may be adapted to select an integration time fordetermining the channel estimates, for example. The processor may alsobe adapted to configure the single chip in the OFDM receiver to handleat least one of a plurality of communication protocols based on OFDM.These communication protocols may comprise an IEEE 802.11 wireless localarea network (WLAN) protocol, an IEEE 802.16 wireless metropolitan areanetwork (WMAN) protocol, or a digital video broadcasting (DVB) protocol,for example. Circuitry within the single chip may be adapted to updateat least a portion of the channel weights dynamically. Moreover,circuitry within the single chip may be adapted to determine a phase andamplitude component for at least one of the channel weights.

The approach described herein for a reconfigurable OFDM chip supportingsingle weight diversity may result in higher transmission rates forvarious communication standards such as WLAN, WMAN, and/or DVB-H, forexample. Moreover, the collaborative architecture provided may beutilized in wireless devices to support efficient cellular andOFDM-based communication.

Accordingly, the present invention may be realized in hardware,software, or a combination thereof. The present invention may berealized in a centralized fashion in at least one computer system, or ina distributed fashion where different elements may be spread acrossseveral interconnected computer systems. Any kind of computer system orother apparatus adapted for carrying out the methods described hereinmay be suited. A typical combination of hardware and software may be ageneral-purpose computer system with a computer program that, when beingloaded and executed, may control the computer system such that itcarries out the methods described herein.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

What is claimed is:
 1. A method for handling wireless communication, themethod comprising: in an orthogonal frequency division multiplexing(OFDM) receiver: selecting at least one of a plurality of generatedrotation waveforms and at least one of a plurality of generated channelweights, wherein: said plurality of rotation waveforms are generated topreserve an orthogonality of a plurality of signals received at aplurality of receive antennas, and said plurality of channel weights aregenerated to maximize a signal to interference and noise ratio of saidreceiver; and modifying at least one of said plurality of signalsreceived at said plurality of receive antennas based on said selection.2. The method according to claim 1, further comprising: combining saidplurality of signals received at said plurality of receive antennas togenerate a single combined received signal.
 3. The method according toclaim 2, further comprising: determining a plurality of basebandcombined channel estimates based on said generated single combinedreceived signal.
 4. The method according to claim 3, further comprising:selecting an integration time for determining said plurality of basebandcombined channel estimates.
 5. The method according to claim 3, furthercomprising: determining at least one of a plurality of subsequentchannel weights based on said determined plurality of baseband combinedchannel estimates.
 6. The method according to claim 1, furthercomprising: modifying said at least one of said plurality of signalsreceived at said plurality of receive antennas by multiplying a complexconjugate of said selected at least one of said plurality of generatedrotation waveforms with a baseband combined channel estimate.
 7. Themethod according to claim 1, further comprising: configuring said OFDMreceiver to handle at least one of a plurality of communicationprotocols based on OFDM.
 8. The method according to claim 7, whereinsaid at least one of said plurality of communication protocols based onOFDM is an IEEE 802.11 wireless local area network (WLAN) protocol, anIEEE 802.16 wireless metropolitan area network (WMAN) protocol, or adigital video broadcasting (DVB) protocol.
 9. The method according toclaim 1, wherein said plurality of rotation waveforms includes one of aplurality of sine waveforms, a plurality of square waveforms, or aplurality of triangular waveforms.
 10. The method according to claim 1,further comprising: determining a phase and amplitude component for saidat least one of said plurality of channel weights.
 11. A system forhandling wireless communication, the system comprising: an orthogonalfrequency division multiplexing (OFDM) receiver configured to: select atleast one of a plurality of generated rotation waveforms and at leastone of a plurality of generated channel weights, wherein said pluralityof rotation waveforms are generated to preserve an orthogonality of aplurality of signals received at a plurality of receive antennas; andmodify at least one of said plurality of signals received at saidplurality of antennas based on said selection.
 12. The system accordingto claim 11, wherein said OFDM receiver is configured to combine saidplurality of signals received at said plurality of receive antennas togenerate a single combined received signal.
 13. The system according toclaim 12, wherein said OFDM receiver is configured to determine aplurality of baseband combined channel estimates based on said generatedsingle combined received signal.
 14. The system according to claim 13,wherein said OFDM receiver is configured to select an integration timefor determining said plurality of baseband combined channel estimates.15. The system according to claim 13, wherein said OFDM receiver isconfigured to determine at least one of a plurality of subsequentchannel weights based on said determined plurality of baseband combinedchannel estimates.
 16. The system according to claim 11, wherein saidOFDM receiver is configured to modify said at least one of saidplurality of signals received at said plurality of receive antennas bymultiplying a complex conjugate of said selected at least one of saidplurality of generated rotation waveforms with a baseband combinedchannel estimate.
 17. The system according to claim 11, wherein saidOFDM receiver is configured to configure said OFDM receiver to handle atleast one of a plurality of communication protocols based on OFDM. 18.The system according to claim 17, wherein said at least one of saidplurality of communication protocols based on OFDM is an IEEE 802.11wireless local area network (WLAN) protocol, an IEEE 802.16 wirelessmetropolitan area network (WMAN) protocol, or a digital videobroadcasting (DVB) protocol.
 19. The system according to claim 11,wherein said plurality of rotation waveforms includes one of a pluralityof sine waveforms, a plurality of square waveforms, or a plurality oftriangular waveforms.
 20. The system according to claim 11, wherein saidOFDM receiver is configured to determine a phase and amplitude componentfor said at least one of said plurality of channel weights.